Micro-electro-mechanical systems (MEMS) has led to the creation of a wide variety of small and fragile electrical components such as sensor technologies. Presently, these MEMS sensors are not typically compatible with standard integrated circuit (IC) packaging technologies because of their fragility. Some have considered going to wafer level packaging for such MEMS sensors, where the MEMS sensor is encapsulated as part of typical clean room processing by a bonding method such as using direct wafer bonding or anodic bonding of a glass or silicon protective cap over the MEMS sensor.
One prior art method involves mounting a MEMS sensor to a silicon wafer or substrate and enclosing the MEMS sensor with a glass or silicon cap, such as the method described in US Patent Application No. 2006/0275946 A1, the contents of which are incorporated herein by reference, where permitted. An electrical lead is run across the surface of the substrate from the MEMS sensor or other electrical component. Routing the electrical connection through the cap is difficult and the interface between the cap and the electrical connector often leads to an imperfect seal or problems with conductivity of the electrical connector.
There is a need in the art for a semiconductor device having through-wafer conductive vias for connecting to an electrical component such as a MEMS sensor from beneath or above the semiconductor substrate. It is also desirable to form the through-wafer conductive vias using the semiconductor substrate material itself so as to minimize a fill process.